1 Field
The present disclosure relates generally to telecommunications, and more particularly, to methods and apparatuses for seamless and efficient wireless handoffs.
2 Background
In conventional wireless communications, an access network is generally employed to connect any number of wireless communications devices or access terminals to wide area networks, such as the Internet or a Public Switched Telephone Network (PSTN). The access network is typically implemented with multiple fixed-site Base Transceiver Stations (BTS) dispersed throughout a geographic region. The geographic region is generally subdivided into smaller regions known as cells. Each BTS may be configured to provide a point of access to various wide area networks for all terminals in its respective cell. As such, the BTS is often referred to as an “access point”. A Base Station Controller (BSC) within the access network is often used to interface each access point to the various gateways to the wide area networks. By way of example, the BSC may provide access to the Internet, or other packet-based networks, through a Packet Data Serving Node (PDSN). The BSC may also provide access to a PSTN, or other circuit-switched networks, through a Mobile Switching Center (MSC). Because the BSC is conceptually positioned at the edge of the access network, it is often referred to as an “edge function”.
Each access point includes a physical layer to support an air interface with the access terminals in its cellular region. A Radio Link Protocol (RLP) above the physical layer in the access point may be used to provide for greater reliability for data transmission. In particular, the RLP interface between the access point and an access terminal provides for the retransmission of data to achieve a lower higher layer packet error rate than the physical layer could achieve alone. In the access point, the RLP may also fragment higher layer packets from the edge function into physical layer frames for over the air transmission on the forward link. The “forward link” refers to transmissions from the access point to the access terminal, and the “reverse link” refers to transmissions from the access terminal to the access point. In the reverse direction, the RLP reassembles physical layer frames it receives from the access terminal into higher level packets for transmission to the edge function.
As the access terminal roams through the access network, it may need to be handed off from a serving access point to a target access point. During handoff, the access terminal terminates the RLP interface with the serving access point and establishes a new RLP interface with the target access point. The process of tearing down and reestablishing a RLP interface may reduce efficiency and causes undesirable latencies during handoff.